linux-kernel - [PATCH] KVM: arm: Enable emulation of the physical timer

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Date:   Tue, 13 Feb 2018 11:41:16 +0100
From:   Jérémy Fanguède 
        <j.fanguede@...tualopensystems.com>
To:     Christoffer Dall <christoffer.dall@...aro.org>,
        Marc Zyngier <marc.zyngier@....com>,
        Russell King <linux@...linux.org.uk>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org
Cc:     tech@...tualopensystems.com,
        Jérémy Fanguède 
        <j.fanguede@...tualopensystems.com>
Subject: [PATCH] KVM: arm: Enable emulation of the physical timer

Set the handlers to emulate read and write operations for CNTP_CTL,
CNTP_CVAL and CNTP_TVAL registers in such a way that VMs can use the
physical timer.

Signed-off-by: Jérémy Fanguède <j.fanguede@...tualopensystems.com>
---

This patch is the equivalent of this one: [1], but for arm 32bits
instead of ARMv8 aarch32.

[1] https://patchwork.kernel.org/patch/10207019/

---
 arch/arm/kvm/coproc.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/arch/arm/kvm/coproc.c b/arch/arm/kvm/coproc.c
index 6d1d2e2..3a02e76 100644
--- a/arch/arm/kvm/coproc.c
+++ b/arch/arm/kvm/coproc.c
@@ -270,6 +270,60 @@ static bool access_gic_sre(struct kvm_vcpu *vcpu,
 	return true;
 }
 
+static bool access_cntp_tval(struct kvm_vcpu *vcpu,
+			     const struct coproc_params *p,
+			     const struct coproc_reg *r)
+{
+	u64 now = kvm_phys_timer_read();
+	u64 val;
+
+	if (p->is_write) {
+		val = *vcpu_reg(vcpu, p->Rt1);
+		kvm_arm_timer_set_reg(vcpu, KVM_REG_ARM_PTIMER_CVAL, val + now);
+	} else {
+		val = kvm_arm_timer_get_reg(vcpu, KVM_REG_ARM_PTIMER_CVAL);
+		*vcpu_reg(vcpu, p->Rt1) = val - now;
+	}
+
+	return true;
+}
+
+static bool access_cntp_ctl(struct kvm_vcpu *vcpu,
+			    const struct coproc_params *p,
+			    const struct coproc_reg *r)
+{
+	u32 val;
+
+	if (p->is_write) {
+		val = *vcpu_reg(vcpu, p->Rt1);
+		kvm_arm_timer_set_reg(vcpu, KVM_REG_ARM_PTIMER_CTL, val);
+	} else {
+		val = kvm_arm_timer_get_reg(vcpu, KVM_REG_ARM_PTIMER_CTL);
+		*vcpu_reg(vcpu, p->Rt1) = val;
+	}
+
+	return true;
+}
+
+static bool access_cntp_cval(struct kvm_vcpu *vcpu,
+			     const struct coproc_params *p,
+			     const struct coproc_reg *r)
+{
+	u64 val;
+
+	if (p->is_write) {
+		val = (u64)*vcpu_reg(vcpu, p->Rt2) << 32;
+		val |= *vcpu_reg(vcpu, p->Rt1);
+		kvm_arm_timer_set_reg(vcpu, KVM_REG_ARM_PTIMER_CVAL, val);
+	} else {
+		val = kvm_arm_timer_get_reg(vcpu, KVM_REG_ARM_PTIMER_CVAL);
+		*vcpu_reg(vcpu, p->Rt1) = val;
+		*vcpu_reg(vcpu, p->Rt2) = val >> 32;
+	}
+
+	return true;
+}
+
 /*
  * We could trap ID_DFR0 and tell the guest we don't support performance
  * monitoring.  Unfortunately the patch to make the kernel check ID_DFR0 was
@@ -423,10 +477,17 @@ static const struct coproc_reg cp15_regs[] = {
 	{ CRn(13), CRm( 0), Op1( 0), Op2( 4), is32,
 			NULL, reset_unknown, c13_TID_PRIV },
 
+	/* CNTP */
+	{ CRm64(14), Op1( 2), is64, access_cntp_cval},
+
 	/* CNTKCTL: swapped by interrupt.S. */
 	{ CRn(14), CRm( 1), Op1( 0), Op2( 0), is32,
 			NULL, reset_val, c14_CNTKCTL, 0x00000000 },
 
+	/* CNTP */
+	{ CRn(14), CRm( 2), Op1( 0), Op2( 0), is32, access_cntp_tval },
+	{ CRn(14), CRm( 2), Op1( 0), Op2( 1), is32, access_cntp_ctl },
+
 	/* The Configuration Base Address Register. */
 	{ CRn(15), CRm( 0), Op1( 4), Op2( 0), is32, access_cbar},
 };
-- 
2.7.4